I noticed that in New Super Mario Bros Wii (and DS), the characters are shaded differently in some levels.In the castle, it looks like light comes from the bottom (see the toad's chin):For comparison, another level (see the yellow toad):

I think that something like this could be added to supertux, too.The current lighting could be called Ambient Light and the directional light can be denoted as Directional Light.For each level, the ratio between Ambient and Directional Light can be set, e.g. low Directional Light in foggy levels. The sun light vector is another additional setting which is used for the Directional Light.To calculate the Directional Light, for each texture (also tiles, not only Tux and enemies) a normalmap defines the normal vectors. If the normalmap is missing, the texture is simply assumed to be flat. Since supertux is 2D, light sources (e.g. a lamp) are modelled approximately as a stripe which goes in -z direction. When calculating the Directional Light for a pixel, the minimum angle between the normal (from the normalmap) and a vector to the light source (which directs to the stripe) is used. (directional light similar to Gouraud shading)Much of the lighting does not need to be calculated dynamically in every frame; for non-moving light sources, it can be calculated when loading the level or combining the tiles. Directional Light for moving light sources can be disabled so that light calculation is not needed for every frame (for performance).

Many current textures are already lighted directionally (with fixed direction), so when enabling Directional Light, different ones need to be used.

So what you're saying is we get 3D lighting for the game so we can light anything from whatever direction with any colour? The only way I can see that working is if we made every art asset in the game shadeless and then gave them a bump map to represent where light would hit them, like the enemies in Super Mario Maker (NSMBU) for example. That sounds really cool in theory but way to hard to make in practice. It would be cool though.

Alzter {l Wrote}:So what you're saying is we get 3D lighting for the game so we can light anything from whatever direction with any colour? The only way I can see that working is if we made every art asset in the game shadeless and then gave them a bump map to represent where light would hit them, like the enemies in Super Mario Maker (NSMBU) for example. That sounds really cool in theory but way to hard to make in practice. It would be cool though.

I'd like to have it combined with the current 2d lighting, which suits better for foggy/cloudy levels.Making every art asset shadeless at once is too much work and may cause compatibility problems. The Directional Light feature could be made an optional setting. If it's disabled, the current shaded textures are used, and if it is enabled, either shadeless textures with their normalmap or a simple copy-paste duplicate of the shaded texture with flat normalmap is used.In time, the duplicates can be changed to be shadeless and have a normalmap. By still using the shaded textures, it's possible to add and test a new texture before creating the normalmap, and it shouldn't be hard to implement in practice I think.